Separation detector

ABSTRACT

Separation of mating faces in a pattern for forming sand molds is detected by blowing air into a passage through one of the mold halves terminating against the parting face of the other mold half and by measuring the pressure in the passage. Apparatus for performing this detection has a tube slidable in and out against a connection on the pattern leading to the passage. Air is supplied to this tube under control of an on-off valve at a constant pressure source through a control orifice. A pressure sensor is connected to the tube. The tube is slidably mounted in a bracket and is moved against the mold or away from it by a double-acting hydraulic cylinder. The bracket is pivoted to a fixed support so that the tube can follow movement of the pattern while maintaining pressuretight connection with it.

United States Patent Assistant Examiner-Wil|iam A. Henry, II Attorney-Theodore L. Chisholm ABSTRACT: Separation of mating faces in a pattern for forming sand molds is detected by blowing air into a passage through one of the mold halves terminating against the parting face of the other mold half and by measuring the pressure in the passage. Apparatus for performing this detection has a tube slidable in and out against a connection on the pattern leading to the passage. Air is supplied to this tube under control of an on-off valve at a constant pressure source through a control orifice. A pressure sensor is connected to the tube. The tube is slidably mounted in a bracket and is moved against the mold or away from it by a double-acting hydraulic cylinder. The bracket is pivoted to a fixed support so that the tube can follow movement of the pattern while maintaining pressuretight connection with it.

SEPARATION DETECTOR This invention relates to separable patterns for forming expendable molds such as shell molds formed of sand. Such patterns normally include two patterns halves or parts each of which has a parting surface. The parting surfaces are pressed against each other to close the pattern and are separated to remove finished molds. Such molds are customarily made of sand treated with a bonder. It sometimes happens that sand from the molds or other dust gets onto the parting surfaces and holds the parts of the pattern apart when they should be tightly in contact throughout the parting surfaces. This causes inaccurate molds.

One of the objects of the invention is to provide a detecting method and apparatus by which such minutely separated patterns can be detected, and if desired, rejected in a continuous process of forming molds.

More specifically it is an object of the invention to provide a simple, reliable, economical apparatus suitable for use in the repetitive and cyclical production of molds in permanent patterns in a more or less continuous process.

It is particularly an object of the invention to provide means for supplying fluid under pressure, such as air, to the patterns and to provide an apparatus which will follow movements of a pattern while maintaining a fluidtight connection with it.

These and other objects of the invention will be understood from the following description and from the accompanying drawings which disclose, for illustration only and not by way of limitation, one way of performing the invention and one form of apparatus for carrying out the method.

FIG. 1 is an elevation partly in section of a portion of a pattern and of a separation detector applied to the pattern, pressure fluid connections and electrical connections being shown schematically.

FlG. 2 is a plan view of the structure shown in FIG. 1.

FM]. 3 is a section on the line 3-3 of FIG. 2.

Referring in detail to the drawings and 12 are top and bottom halves of a permanent pattern which mate at a parting plane indicated by the line 14. When the halves are accurately mated they form a complete pattern having a known cavity, not shown, into which sand may be blown to form a shell mold, for example, as is known in the art. A number of complete molds may be mounted on a rotary transfer table 116 as shown for example in the US. Re. Pat. No. 26,218 to Earl A. Thompson, June 6, 1967. A number of patterns may be supported on the edge of such a table corresponding to the fixtures 114 in FIGS. 1 and 2 of that patent. The table is rotated intermittently as disclosed therein and when it comes to rest individual patterns at the several stations are in position to have various operations performed such as coating the mold cavities with parting agents, blowing sand into the patterns and opening the patterns for removal of the finished molds, closing the patterns, and testing them for accurate mating all as more fully disclosed in my application for United States patent executed of even date herewith jointly with Elizabeth F. Thompson, Paul Franseth and Michael M. Wild, Executors, titled MAlUNG 163 MOLDS, the disclosure of which is incorporated herein by reference.

Each pattern has a passage 18 from outside the pattern through one of the pattern halves to its parting plane. This pattern part is provided with a suitable surface or fitting 20 by which air can be blown into the passage. Preferably air is blown into the passage from a lance in the form of a tube 22 slidable toward and away from the pattern in a guide '24 secured to the front end of a bracket 26 pivoted at 28 to a fixed support 30.

One of the fittings, for example 20, has a spherical surface 32 while the other fitting has a mating conical surface 34 to allow small angular movements between the fittings while preserving a pressuretight connection.

The lance also includes a piston 35 not shown, but corresponding to the piston Mill in said Reissue patent FIG. ll slidable in a double-acting hydraulic cylinder 36 fixed to the bracket 26. The piston terminates in a red 3155 rigidly joined to the tube 22 by a connecting fitting 40 through which a passage 42 communicates between the interior of the tube 22 and a fluid pressure supply pipe 43 having an on-off valve 44 operated by a double-acting hydraulic cylinder 45. The rod 38, connection 40 and tube 22 together form a rigid lance which can slide against the fitting 20 and away from it under the influence of the double acting hydraulic cylinder 36 which also forms a rear bearing for the sliding lance cooperating with the front bearing in the guide 24.

The air supply pipe 43 is connected through a calibrated control orifice or restriction 46 which is supplied by air at a constant pressure determined by a pressure regulator 48 connected to a source of supply 50. Pressure in the supply pipe 43, which is also a measure of the pressure in the passage lid is measured in any suitable way. Whenever the pattern halves are accurately mated the pressure in the passage 18 and consequently in the supply pipe 40 will be substantially as the same as the pressure supplied by the pressure regulator 48. if the pattern halves are slightly separated the pressure in the passage 18 will be less than the pressure supplied by the regulator 48. Difference in pressure at these points is an indication that the mold is open. This difference can be measured in any suitable way but preferably l measure the absolute value of the pressure on the downstream side of the control orifice 46 by any suitable pressure sensor such as: a flexible diaphragm 52 clamped between the cup-shaped halves of a casing 54 and supporting a rod 56 connected to a switch 58 in an electrical control circuit 64).

When air under pressure is supplied to the passage 18 and the pattern is accurately closed the pressure will remain high, the diaphragm 52 will be pushed up and the switch 58 will remain open. An open switch indicates a satisfactorily closed pattern. However if the pattern is held slightly open, for example by grains of dust or sand between. the parting surfaces, the pressure in the passage lb will fall, the diaphragm 52 will drop, the switch will be closed and will actuate any suitable visual or audible alarm 62 and any suitable rejection device 64 or both. The rejection device may be any suitable mechanism which either physically removes an open pattern from proximity to the parting agent blowing devices and sand blowing devices or allows the separated mold to pass by these devices without allowing the devices to operate.

ln various types of installation it may be desirable to move the mold either vertically or horizontally during the time the lance is in contact with the fitting 20. The drawings illustrate provision for allowing vertical movement of the mold. This is the pivot 23 referred to which rotatably supports the entire lance, its support, and its operating cylinder by being attached to the bracket 26.

It is contemplated that the lance will tip up and down, falling by its own weight into proper position to establish contact between the connections 32 and 20 when the cylinder 36 advances the lance to the full line position shown in FIG. ii. The precise position of the probe when dropped can be determined by any suitable adjustable stop bb. The dotted line position indicates schematically the lance in its elevated position.

in operation a number of patterns ill-12 will be supported along the edge of the transfer table shown in US. Re. Pat. No. 26,218 and the table will be intermittently rotated and stopped to have various operations performed on the patterns as explained above. At one of the stations a pattern will stop opposite the connection 32, the cylinder 36 will be pressurized to put the connection 32 against the connection 20, and the cylinder 45 will be pressurized to open the valve 44. Then if the pattern is closed the switch 58 will remain open and the automatic process of advancing the table will continue. However if the switch 58 closes indicating an open pattern the signal 62 will operate as well as the rejection device at. This rejection device may cause this particular pattern to pass by any desired stations adjacent the transfer table without operation of the devices at these stations. At an appropriate and convenient time in the cycle the open mold may be removed, cleaned or replaced as may be required.

I claim as my invention:

1. The method of operating a pattern having abuttable and separable parts each of which has a parting surface for mating with the parting surface of the other part, which method includes having a passage through one part which passage has an open end in the parting surface of that part, nominally closing the pattern, directing fluid from a source of pressure through the passage toward said open end while measuring the difference in pressure between the source and said passage and rejecting the pattern when the difference in pressure is above a predetermined amount,

2. The method of operating a pattern having abuttable and separable parts each of which has a parting surface for mating with the parting surface of the other part which method includes having a passage through one part which passage has an open end in the parting surface of that one part, nominally closing the pattern, directing fluid from a constant pressure source through the passage toward said open end while measuring the pressure in said passage, and rejecting the pattern when the pressure in the passage is below a predetermined amount.

3. Apparatus for detecting separation of patterns comprising in combination a pattern having two abuttable and separable parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part including a first connector communicating with the passage for conducting pressure fluid to the passage, a second connector communicating with a source of pressure for forming a pressurctight connection with the first connector, a control orifice between the pressure source and the connectors, and means for measuring difference in pressure between the source and the passage.

4. Apparatus for detecting separation of patterns comprising in combination a pattern having two abuttable and separable parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part including a first connector communicating with the passage for conducting pressure fluid to the passage, a second connector communicating with a source of constant pressure for forming a pressuretight connection with the first connector, a control orifice between the pressure source and the connectors, and means for measuring pressure in the passage.

5. Apparatus for detecting separation of patterns comprising in combination a pattern having two abuttable and separable parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part including a first connector communicating with the passage for conduct ing pressure fluid to the passage, a second connector communicating with a source of constant pressure, means for moving the second connector against the first connector for forming a pressuretight connection between the connectors, a control orifice between the pressure source and the connectors, and means for measuring pressure in the passage.

6. Apparatus for detecting separation of patterns comprising in combination a pattern having two abuttable and separable parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part including a first connector communicating with the passage for conducting pressure fluid to the passage, a second connector commu' nicating with a source of pressure for forming a pressuretight connection with the first connector, a tube carrying the second connector and means for moving the tube selectively against and away from the first connector.

7. Apparatus for detecting separation of patterns comprising in combination a pattern having two parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part including a first connector communicating with the passage for conducting pressure fluid to the passage, a second connector communicating with a source of pressure for forming a pressuretight connection with the first connector, a tube carrying the second connector, means for moving the tube selectively away from and against the connector and means permitting rocking of the tube in a direction transverse to its length to follow the first connector as the pattern moves. 

1. The method of operating a pattern having abuttable and separable parts each of which has a parting surface for mating with the parting surface of the other part, which method includes having a passage through one part which passage has an open end in the parting surface of that part, nominally closing the pattern, directing fluid from a source of pressure through the passage toward said open end while measuring the difference in pressure between the source and said passage and rejecting the pattern when the difference in pressure is above a predetermined amount.
 2. The method of operating a pattern having abuttable and separable parts each of which has a parting surface for mating with the parting surface of the other part which method includes having a passage through one part which passage has an open end in the parting surface of that one part, nominally closing the pattern, directing fluid from a constant pressure source through the passage toward said open end while measuring the pressure in said passage, and rejecting the pattern when the pressure in the passage is below a predetermined amount.
 3. Apparatus for detecting separation of patterns comprising in combination a pattern having two abuttable and separable parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part including a first connector communicating with the passage for conducting pressure fluid to the passage, a second connector communicating with a source of pressure for forming a pressuretight connection with the first connector, a control orifice between the pressure source and the connectors, and means for measuring difference in pressure between the source and the passage.
 4. Apparatus for detecting separation of patterns comprising in combination a pattern having two abuttable and separable parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part inclUding a first connector communicating with the passage for conducting pressure fluid to the passage, a second connector communicating with a source of constant pressure for forming a pressuretight connection with the first connector, a control orifice between the pressure source and the connectors, and means for measuring pressure in the passage.
 5. Apparatus for detecting separation of patterns comprising in combination a pattern having two abuttable and separable parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part including a first connector communicating with the passage for conducting pressure fluid to the passage, a second connector communicating with a source of constant pressure, means for moving the second connector against the first connector for forming a pressuretight connection between the connectors, a control orifice between the pressure source and the connectors, and means for measuring pressure in the passage.
 6. Apparatus for detecting separation of patterns comprising in combination a pattern having two abuttable and separable parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part including a first connector communicating with the passage for conducting pressure fluid to the passage, a second connector communicating with a source of pressure for forming a pressuretight connection with the first connector, a tube carrying the second connector and means for moving the tube selectively against and away from the first connector.
 7. Apparatus for detecting separation of patterns comprising in combination a pattern having two parts each having a parting surface for mating with the parting surface of the other, a passage in one part through its parting surface and adapted to be blocked by the other parting surface when the parts are mated, said one part including a first connector communicating with the passage for conducting pressure fluid to the passage, a second connector communicating with a source of pressure for forming a pressuretight connection with the first connector, a tube carrying the second connector, means for moving the tube selectively away from and against the connector and means permitting rocking of the tube in a direction transverse to its length to follow the first connector as the pattern moves. 